Downhole drilling motors (also referred to as “mud motors”) are commonly used in the oil and gas industry in drilling wellbores for the extraction of hydrocarbons from subterranean regions. A typical downhole drilling motor includes a motor suspended near the lower end of a string of drill pipe supported from a well surface location, such as a land-based or sea-based drilling rig. The motor includes a rotatable driveshaft that is directly or indirectly coupled to a rotary drill bit, such as a fixed cutter drill bit, a roller cone drill bit, a reamer, etc. The motor operates by circulating drilling fluid or “mud” through the drill pipe and into the motor, which generates torque that causes the driveshaft to rotate and thereby correspondingly rotate the drill bit.
Drilling motors typically include bearing assemblies that help facilitate rotation of the driveshaft during operation. Most bearing assemblies in drilling motors include thrust bearings that assume axial loading and radial bearings that assume radial loading. The thrust and radial bearings each include bearing surfaces that at least partially contact and move or slide relative to opposing bearing surfaces to maintain smooth rotation and operation of the drilling motor. Such bearing surfaces may comprise ultra-hard (super hard) materials for resisting wear during prolonged use. Geometry and configuration of the bearing assemblies are an important factor influencing the performance and life of drilling motors.